1 /* 2 * linux/drivers/leds-pwm.c 3 * 4 * simple PWM based LED control 5 * 6 * Copyright 2009 Luotao Fu @ Pengutronix (l.fu@pengutronix.de) 7 * 8 * based on leds-gpio.c by Raphael Assenat <raph@8d.com> 9 * 10 * This program is free software; you can redistribute it and/or modify 11 * it under the terms of the GNU General Public License version 2 as 12 * published by the Free Software Foundation. 13 */ 14 15 #include <linux/module.h> 16 #include <linux/kernel.h> 17 #include <linux/init.h> 18 #include <linux/platform_device.h> 19 #include <linux/of_platform.h> 20 #include <linux/fb.h> 21 #include <linux/leds.h> 22 #include <linux/err.h> 23 #include <linux/pwm.h> 24 #include <linux/leds_pwm.h> 25 #include <linux/slab.h> 26 #include <linux/workqueue.h> 27 28 struct led_pwm_data { 29 struct led_classdev cdev; 30 struct pwm_device *pwm; 31 struct work_struct work; 32 unsigned int active_low; 33 unsigned int period; 34 int duty; 35 bool can_sleep; 36 }; 37 38 struct led_pwm_priv { 39 int num_leds; 40 struct led_pwm_data leds[0]; 41 }; 42 43 static void __led_pwm_set(struct led_pwm_data *led_dat) 44 { 45 int new_duty = led_dat->duty; 46 47 pwm_config(led_dat->pwm, new_duty, led_dat->period); 48 49 if (new_duty == 0) 50 pwm_disable(led_dat->pwm); 51 else 52 pwm_enable(led_dat->pwm); 53 } 54 55 static void led_pwm_work(struct work_struct *work) 56 { 57 struct led_pwm_data *led_dat = 58 container_of(work, struct led_pwm_data, work); 59 60 __led_pwm_set(led_dat); 61 } 62 63 static void led_pwm_set(struct led_classdev *led_cdev, 64 enum led_brightness brightness) 65 { 66 struct led_pwm_data *led_dat = 67 container_of(led_cdev, struct led_pwm_data, cdev); 68 unsigned int max = led_dat->cdev.max_brightness; 69 unsigned int period = led_dat->period; 70 71 led_dat->duty = brightness * period / max; 72 73 if (led_dat->can_sleep) 74 schedule_work(&led_dat->work); 75 else 76 __led_pwm_set(led_dat); 77 } 78 79 static inline size_t sizeof_pwm_leds_priv(int num_leds) 80 { 81 return sizeof(struct led_pwm_priv) + 82 (sizeof(struct led_pwm_data) * num_leds); 83 } 84 85 static int led_pwm_create_of(struct platform_device *pdev, 86 struct led_pwm_priv *priv) 87 { 88 struct device_node *node = pdev->dev.of_node; 89 struct device_node *child; 90 int ret; 91 92 for_each_child_of_node(node, child) { 93 struct led_pwm_data *led_dat = &priv->leds[priv->num_leds]; 94 95 led_dat->cdev.name = of_get_property(child, "label", 96 NULL) ? : child->name; 97 98 led_dat->pwm = devm_of_pwm_get(&pdev->dev, child, NULL); 99 if (IS_ERR(led_dat->pwm)) { 100 dev_err(&pdev->dev, "unable to request PWM for %s\n", 101 led_dat->cdev.name); 102 ret = PTR_ERR(led_dat->pwm); 103 goto err; 104 } 105 /* Get the period from PWM core when n*/ 106 led_dat->period = pwm_get_period(led_dat->pwm); 107 108 led_dat->cdev.default_trigger = of_get_property(child, 109 "linux,default-trigger", NULL); 110 of_property_read_u32(child, "max-brightness", 111 &led_dat->cdev.max_brightness); 112 113 led_dat->cdev.brightness_set = led_pwm_set; 114 led_dat->cdev.brightness = LED_OFF; 115 led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME; 116 117 led_dat->can_sleep = pwm_can_sleep(led_dat->pwm); 118 if (led_dat->can_sleep) 119 INIT_WORK(&led_dat->work, led_pwm_work); 120 121 ret = led_classdev_register(&pdev->dev, &led_dat->cdev); 122 if (ret < 0) { 123 dev_err(&pdev->dev, "failed to register for %s\n", 124 led_dat->cdev.name); 125 of_node_put(child); 126 goto err; 127 } 128 priv->num_leds++; 129 } 130 131 return 0; 132 err: 133 while (priv->num_leds--) 134 led_classdev_unregister(&priv->leds[priv->num_leds].cdev); 135 136 return ret; 137 } 138 139 static int led_pwm_probe(struct platform_device *pdev) 140 { 141 struct led_pwm_platform_data *pdata = dev_get_platdata(&pdev->dev); 142 struct led_pwm_priv *priv; 143 int count, i; 144 int ret = 0; 145 146 if (pdata) 147 count = pdata->num_leds; 148 else 149 count = of_get_child_count(pdev->dev.of_node); 150 151 if (!count) 152 return -EINVAL; 153 154 priv = devm_kzalloc(&pdev->dev, sizeof_pwm_leds_priv(count), 155 GFP_KERNEL); 156 if (!priv) 157 return -ENOMEM; 158 159 if (pdata) { 160 for (i = 0; i < count; i++) { 161 struct led_pwm *cur_led = &pdata->leds[i]; 162 struct led_pwm_data *led_dat = &priv->leds[i]; 163 164 led_dat->pwm = devm_pwm_get(&pdev->dev, cur_led->name); 165 if (IS_ERR(led_dat->pwm)) { 166 ret = PTR_ERR(led_dat->pwm); 167 dev_err(&pdev->dev, 168 "unable to request PWM for %s\n", 169 cur_led->name); 170 goto err; 171 } 172 173 led_dat->cdev.name = cur_led->name; 174 led_dat->cdev.default_trigger = cur_led->default_trigger; 175 led_dat->active_low = cur_led->active_low; 176 led_dat->period = cur_led->pwm_period_ns; 177 led_dat->cdev.brightness_set = led_pwm_set; 178 led_dat->cdev.brightness = LED_OFF; 179 led_dat->cdev.max_brightness = cur_led->max_brightness; 180 led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME; 181 182 led_dat->can_sleep = pwm_can_sleep(led_dat->pwm); 183 if (led_dat->can_sleep) 184 INIT_WORK(&led_dat->work, led_pwm_work); 185 186 ret = led_classdev_register(&pdev->dev, &led_dat->cdev); 187 if (ret < 0) 188 goto err; 189 } 190 priv->num_leds = count; 191 } else { 192 ret = led_pwm_create_of(pdev, priv); 193 if (ret) 194 return ret; 195 } 196 197 platform_set_drvdata(pdev, priv); 198 199 return 0; 200 201 err: 202 while (i--) 203 led_classdev_unregister(&priv->leds[i].cdev); 204 205 return ret; 206 } 207 208 static int led_pwm_remove(struct platform_device *pdev) 209 { 210 struct led_pwm_priv *priv = platform_get_drvdata(pdev); 211 int i; 212 213 for (i = 0; i < priv->num_leds; i++) { 214 led_classdev_unregister(&priv->leds[i].cdev); 215 if (priv->leds[i].can_sleep) 216 cancel_work_sync(&priv->leds[i].work); 217 } 218 219 return 0; 220 } 221 222 static const struct of_device_id of_pwm_leds_match[] = { 223 { .compatible = "pwm-leds", }, 224 {}, 225 }; 226 MODULE_DEVICE_TABLE(of, of_pwm_leds_match); 227 228 static struct platform_driver led_pwm_driver = { 229 .probe = led_pwm_probe, 230 .remove = led_pwm_remove, 231 .driver = { 232 .name = "leds_pwm", 233 .owner = THIS_MODULE, 234 .of_match_table = of_pwm_leds_match, 235 }, 236 }; 237 238 module_platform_driver(led_pwm_driver); 239 240 MODULE_AUTHOR("Luotao Fu <l.fu@pengutronix.de>"); 241 MODULE_DESCRIPTION("PWM LED driver for PXA"); 242 MODULE_LICENSE("GPL"); 243 MODULE_ALIAS("platform:leds-pwm"); 244